Letrozole

Definition

A nonsteroidal inhibitor of estrogen synthesis with antineoplastic activity. As a third-generation aromatase inhibitor, letrozole selectively and reversibly inhibits aromatase, which may result in growth inhibition of estrogen-dependent breast cancer cells. Aromatase, a cytochrome P-450 enzyme localized to the endoplasmic reticulum of the cell and found in many tissues including those of the premenopausal ovary, liver, and breast, catalyzes the aromatization of androstenedione and testosterone into estrone and estradiol, the final step in estrogen biosynthesis.

Also known as 4,4'-(1H-1,2,4triazol-1-ylmethylene)dibenzonitrile, CGS 20267, CGS-20267, CGS20267, Femara, Fempro, LETROZOLE — per NCIT

Also identified as

• ATC L02BG per NCIT
• NCIT NCIT:C1527 per NCIT

Indications